Abstract: In order to solve the problem of high energy consumption of relay communication and high difficulty in the construction of 5G base stations, the research on Reconfigurable Intelligent Surface (RIS) technology was introduced in 6G mobile communication. Aiming at the problem of characteristic loss and instability of the truncated Hadamard matrix and Discrete Fourier Transform (DFT) matrix when constructing intelligent surfaces, a new RIS phase shift model design scheme of constructing unitary matrix based on Hankel matrix and Toeplitz matrix was proposed. The characteristics of the unitary matrix were used to minimize the channel error and improve the reliability of the communication channel. The simulation results show that compared with that of non-RIS-assisted communication, the user receiving rate of RIS-assisted communication can obtain a gain of 1 (bit·s^-1)/Hz when the number of RIS units is 15. With the increase of the number of RIS units, the gain of the user receiving rate will be more and more significant. When the number of RIS units is 4, compared to the method of using DFT matrix to construct intelligent reflecting surfaces, the methods of using the two obtained unitary matrices to construct reflecting surfaces have higher reliability, and can obtain the performance gain of about 0.5 dB.

Key words: Reconfigurable Intelligent Surface (RIS), 6th-Generation (6G) communication, Hadamard matrix, optimal phase shift, unitary matrix

摘要： 为了解决中继通信的耗能高以及5G基站的建设难度高的问题，在6G移动通信中引入对可重构智能表面（RIS）技术的研究。针对截断的哈达玛（Hadamard）矩阵和离散傅里叶变换（DFT）矩阵在构建智能表面时失去特性和不稳定问题，提出一种基于汉克尔（Hankel）矩阵和托普利兹（Toeplitz）矩阵来构建酉矩阵的RIS相移模型设计方案。利用酉矩阵的特性来最小化信道误差，提高通信信道的可靠性。仿真结果表明，在RIS单元数为15时，相较于非RIS辅助通信，RIS辅助通信的用户速率可以获得1 （bit·s^-1）/Hz的增益，而伴随着RIS单元数的增加，RIS辅助通信的用户接收速率的增益将更为显著；并且当RIS单元数为4时，相较于DFT矩阵构建智能反射面的方式，利用得到的两个酉矩阵构建的反射面的可靠性更高，约可获得0.5 dB的性能增益。

关键词: 可重构智能表面, 6G通信, 哈达玛矩阵, 最佳相移, 酉矩阵